Video-segment identification systems and methods

ABSTRACT

Summarization segments of an encoded video can be efficiently identified, without the need to decode the encoded video to obtain image data, by analyzing encoded-buffer-size deltas, each indicating an encoded-buffer-size difference between a pair of intra-coded frames of an encoded video.

FIELD

This disclosure is directed to the field of software, and more particularly to efficiently identifying summarization segments of an encoded video without the need to decode the encoded video to obtain image data.

BACKGROUND

Camera phones and other personal digital-video capture devices have become nearly ubiquitous in the early 21st century. As a result, many individuals and entities have acquired sizable libraries of digital video footage, much of it recorded during vacations, parties, or other events.

However, while it is very easy to record video footage, editing and curating one's digital-video library can be a tedious, difficult, and time-consuming chore. Consequently, several approaches to automatic video indexing and segmentation have been developed. Some of these approaches operate on decoded or decompressed image data, detecting scene changes by inspecting pixel values of frames of video. However, most digital video is stored in encoded or compressed format, and decoding compressed video to obtain image data is a relatively computationally expensive operation.

Other approaches operate on encoded or compressed video, analyzing information that is accessible without decoding the video, such as discrete cosine transform (“DCT”) values and motion vectors of successive inter-frames of encoded video.

However, existing approaches tend to be complex and may not scale well. Furthermore, existing approaches that merely identify scene changes within a video do not necessarily provide information about which of the identified scenes may be comparatively interesting to a human observer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a routine for automatically generating a video presentation summarizing one or more encoded videos, such as may be performed by a video-segment identification device in accordance with one embodiment.

FIG. 2 illustrates a subroutine for efficiently identifying summarization segments of a given encoded video without the need to decode the given encoded video to obtain image data, such as may be performed by a video-segment identification device in accordance with one embodiment.

FIG. 3 illustrates a subroutine for identifying a beginning of a summarization segment of a given encoded video based at least in part on a plurality of encoded-buffer-size deltas, each indicating an encoded-buffer-size difference between a pair of intra-coded frames of a sequenced plurality of intra-coded frames, such as may be performed by a video-segment identification device in accordance with one embodiment.

FIG. 4 illustrates a subroutine for identifying an ending of a summarization segment of a given encoded video based at least in part on a plurality of encoded-buffer-size deltas, each indicating an encoded-buffer-size difference between a pair of intra-coded frames of a sequenced plurality of intra-coded frames, such as may be performed by a video-segment identification device in accordance with one embodiment.

FIG. 5 illustrates several exemplary sets of data resulting from various operations such as described herein.

FIG. 6 illustrates several components of an exemplary video-segment identification device in accordance with one embodiment.

DESCRIPTION

The phrases “in one embodiment”, “in various embodiments”, “in some embodiments”, and the like are used repeatedly. Such phrases do not necessarily refer to the same embodiment. The terms “comprising”, “having”, and “including” are synonymous, unless the context dictates otherwise.

Various embodiments, as discussed below, may efficiently detect temporal segments of compressed video that stand out as interesting or significant for human viewing by leveraging analysis performed by video compression algorithms at the time of compression.

Most video-compression algorithms pursue maximum compression while preserving quality and are sensitive to image complexity and to changes in the image over time. The results of the video-compression algorithm's effort are encapsulated in a number of properties of compressed video that can be readily extracted without uncompressing the data, and that can be efficiently analyzed as signals to identify and score temporal segments of video for their visual complexity and motion. Furthermore, such signals, individually or in combination, can be used to identify segments in video that statistically are likely to be of interest to a human observer.

As discussed below, one property of compressed video that can be easily extracted to form signals (time mapped values) is the encoded-buffer size or storage size of intra-frame coded images (also referred to as I-frames or keyframes) that can be decoded independently of any other frames.

Generally, the process of efficiently detecting interesting segments of a compressed video may follow a broad outline similar to the following.

-   -   generating time-domain signal for each property (or combination         of properties) that is readily available from the compressed         video data (without decompressing the data);     -   finding patterns in the time-domain signals to detect temporal         start and end points of a potentially interesting segment;     -   scoring the potentially interesting segments based on signal         characteristics such as signal strength, signal variability,         signal rise, signal decline either within and/or surrounding the         identified segment;     -   when multiple videos are analyzed, normalizing the segment         scores based on characteristic strength of the signals generated         with each video (e.g. using average or RMS method); and     -   selecting, coalescing, cutting, temporally stretching and/or         compacting high scoring segments based on factors such as the         overall presentation duration, desired individual segment         duration, temporal segment separation, or other goal         characteristics of the final presentation.

More particularly, as discussed herein, in various embodiments, a processor and/or processing device may be configured (e.g., via non-transitory computer-readable storage media) to perform a first method for efficiently identifying summarization segments of an encoded video without the need to decode the encoded video to obtain image data, the first method including steps similar to some or all of the following: identifying sequenced intra-coded frames of the encoded video; determining encoded-buffer sizes corresponding respectively to the sequenced intra-coded frames; and selecting summarization segments of the encoded video based at least in part on encoded-buffer-size deltas, each indicating an encoded-buffer-size difference between a pair of intra-coded frames of the sequenced intra-coded frames.

In some embodiments, the first method further includes steps similar to some or all of the following: automatically generating a video presentation summarizing the encoded video, the video presentation including the summarization segments.

In some embodiments, the first method further includes steps similar to some or all of the following: obtaining second summarization segments selected from a second encoded video; scoring the summarization segments and the second summarization segments according to a metric associated with encoded-buffer-size deltas; selecting a first subset of the summarization segments and a second subset of the second summarization segments; and automatically generating a video presentation summarizing the encoded video and the second encoded video, the video presentation including the first selected subset and the second selected subset.

In some embodiments, selecting the summarization segments includes steps similar to some or all of the following: determining that an encoded-buffer-size delta of the encoded-buffer-size deltas exceeds a segment-start threshold; and determining that one of the summarization segments starts at a timestamp associated with the determined encoded-buffer-size delta.

In some embodiments, determining that the determined encoded-buffer-size delta exceeds the segment-start threshold includes steps similar to some or all of the following: selecting a target intra-coded frame; determining a time-window immediately preceding the target intra-coded frame, the time-window including preceding intra-coded frames; selecting a preceding intra-coded frame within the time-window as having a small encoded-buffer size among the preceding intra-coded frames; and determining an encoded-buffer-size delta corresponding to the target intra-coded frame and the preceding intra-coded frame.

In some embodiments, determining that the determined encoded-buffer-size delta exceeds the segment-start threshold includes steps similar to some or all of the following: selecting a target intra-coded frame; determining a time-window immediately preceding the target intra-coded frame, the time-window including preceding intra-coded frames; selecting a preceding intra-coded frame within the time-window as having a large encoded-buffer size among the preceding intra-coded frames; and determining an encoded-buffer-size delta corresponding to the preceding intra-coded frame and the target intra-coded frame.

In some embodiments, selecting the summarization segments includes steps similar to some or all of the following: determining that an encoded-buffer-size delta of the encoded-buffer-size deltas exceeds a segment-end threshold; and determining that one of the summarization segments ends at a timestamp associated with the determined encoded-buffer-size delta.

In some embodiments, selecting the summarization segments includes steps similar to some or all of the following: ensuring that the summarization segments are separated by at least a minimum time-gap.

In some embodiments, selecting the summarization segments includes steps similar to some or all of the following: ensuring that each of the summarization segments are at least a minimum duration in length.

Described more fully below are many additional details, variations, and embodiments that may or may not include some or all of the steps, features, and/or functionality described above.

Reference is now made in detail to the description of the embodiments as illustrated in the drawings. While embodiments are described in connection with the drawings and related descriptions, there is no intent to limit the scope to the embodiments disclosed herein. On the contrary, the intent is to cover all alternatives, modifications and equivalents. In alternate embodiments, additional devices, or combinations of illustrated devices, may be added to, or combined, without limiting the scope to the embodiments disclosed herein.

FIG. 1 illustrates a routine 100 for automatically generating a video presentation summarizing one or more encoded videos, such as may be performed by a video-segment identification device 600 in accordance with one embodiment.

In various embodiments, routine 100 may be performed by a video-capture device such as a smart phone and/or tablet computer to generate a video presentation summarizing one or more encoded videos captured by the video-capture device. In other embodiments, routine 100 may be performed by a personal computer operated by an individual to generate a video presentation summarizing one or more encoded videos captured by the individual using a personal video-capture device. In still other embodiment, routine 100 may be performed by a computing device operated by an individual or entity providing (among other things) automatic encoded video-summarization services for encoded videos captured by others and provided to the computing device for summarization.

In block 105, routine 100 obtains one or more video-presentation parameters, such as an overall presentation duration, desired individual segment duration, temporal segment separation, or other goal characteristics.

In block 110, routine 100 obtains one or more encoded videos. As the term is used herein, an “encoded” video refers to video data that has been encoded or compressed according to a lossy video compressor, such as a video compressor that conforms to a lossy video coding/compression format, such as MPEG-2 Part 2, MPEG-4 Part 2, H.264 (MPEG-4 Part 10), HEVC, Theora, Dirac, RealVideo RV40, VP8, VP9, and the like, that uses a combination of interframe and intraframe compression techniques.

Beginning in opening loop block 115, routine 100 processes each encoded video obtained in block 110 in turn.

In subroutine block 200, routine 100 calls subroutine 200 (see FIG. 2, discussed below) to efficiently identify summarization segments of an encoded video without the need to decode the encoded video to obtain image data. As the term is used herein, “image data” refers in this context to decoded/decompressed data representing values in the spatial/2D/pixel domain of one or more images/frames from a video.

In ending loop block 125, routine 100 iterates back to opening loop block 115 to process the next encoded video obtained in block 110, if any.

In block 130, routine 100 post-processes the summarization segments, typically based at least in part on one or more video-presentation parameters obtained in block 105 and/or on summarization-segment scores such as may be determined in block 230 (see FIG. 2, discussed below).

In some embodiments, routine 100 ensures that a plurality of summarization segments are separated by at least a minimum time-gap and/or that each of the plurality of summarization segments are at least a minimum duration in length. In some embodiments, routine 100 may select, coalesce, cut, stretch, and/or compact high scoring segments consistent with video-presentation parameters obtained in block 105.

In block 135, routine 100 selects some or all of the summarization segments based at least in part on the evaluations performed in block 230 and on video-presentation parameters obtained in block 105.

In block 140, routine 100 automatically generates a video presentation summarizing the encoded videos obtained in block 110, the video presentation including some or all of the summarization segments identified in iterations of subroutine block 200.

Routine 100 ends in ending block 199.

FIG. 2 illustrates a subroutine 200 for efficiently identifying summarization segments of a given encoded video without the need to decode the given encoded video to obtain image data, such as may be performed by a video-segment identification device 600 in accordance with one embodiment.

In block 205, subroutine 200 identifies a sequenced plurality of intra-coded frames of the given encoded video. As the term is used herein, a “intra-coded frame” refers to a frame of the given video that is coded/compressed without reference to macroblocks or similar data from another frame. Intra-coded frames are sometimes called “I-frames” or “keyframes” and are distinguished from “P-frames”, “B-frames” and other interframe-coded pictures that are coded/compressed (at least in part) by reference to another frame of the video. In some encoded videos, intra-coded frames appear at regular intervals, e.g. one intra-coded frame every ‘N’ seconds or every ‘M’ frames. In other encoded videos, intra-coded frames appear at irregular intervals.

In block 210, subroutine 200 initialize summarization-segment data structure(s) initializes one or more data structures representing summarization segments of the given encoded video.

Beginning in opening loop block 215, subroutine 200 processes each all intra-coded frames processed in turn.

In subroutine block 300, subroutine 200 calls subroutine 300 (see FIG. 3, discussed below) to scan for summarization-segment start scan through the remaining intra-coded frames until one is found that satisfies one or more conditions indicative of the start of a summarization segment.

In subroutine block 400, subroutine 200 calls subroutine 400 (see FIG. 4, discussed below) to scan for summarization-segment end scan through the remaining intra-coded frames until one is found that satisfies one or more conditions indicative of the end of a summarization segment.

In block 230, subroutine 200 evaluates the summarization segment evaluates the summarization segment bounded by the segment start identified in subroutine block 300 and the segment end identified in subroutine block 400. In various embodiments, subroutine 200 may evaluate the summarization segment according to various factors, such as the length of the summarization segment, the rate of change in encoded-buffer sizes preceding and/or following the summarization segment, and the like. Summarization segment candidates graph 520 (see FIG. 5, discussed below) illustrates an exemplary set of evaluation values of summarization segments.

In block 235, subroutine 200 updates the summarization-segment-data structure according to the segment start identified in subroutine block 300, the segment end identified in subroutine block 400, and the evaluation performed in block 230.

In ending loop block 240, subroutine 200 iterates back to opening loop block 215 to process the next all intra-coded frames processed, if any.

Subroutine 200 ends in ending block 299, returning the summarization-segment data structure to the caller.

FIG. 3 illustrates a subroutine 300 for identifying a beginning of a summarization segment of a given encoded video based at least in part on a plurality of encoded-buffer-size deltas, each indicating an encoded-buffer-size difference between a pair of intra-coded frames of a sequenced plurality of intra-coded frames, such as may be performed by a video-segment identification device 600 in accordance with one embodiment.

In block 305, subroutine 300 selects the first intra-coded frame of the given encoded video that has not already been processed.

In decision block 310, subroutine 300 determines whether target intra-coded frame selected in block 305 is the first intra-coded frame of the given encoded video.

In block 315, subroutine 300 determines the encoded-buffer size of the target intra-coded frame selected in block 305. The encoded-buffer size of the target intra-coded frame is available without decoding the given encoded video (which is computationally expensive) and represents the quantity of data that the lossy encoder allocated to the target intra-coded frame. Encoded-buffer sizes graph 505 (see FIG. 5, discussed below) illustrates a signal derived from the encoded-buffer sizes of intra-coded frames within an exemplary encoded video.

In block 320, subroutine 300 determines a time-window immediately preceding the target intra-coded frame, the time-window including a plurality of preceding intra-coded frames. In some embodiments, the time-window has a predetermined duration of, for example, between 1-5 seconds. In the exemplary implementation described in Appendix A, the immediately-preceding time-window has a duration of 3.5 seconds.

In block 325, subroutine 300 selects the preceding intra-coded frame within a time-window as having a small encoded-buffer size among a plurality of preceding intra-coded frames.

In block 330, subroutine 300 determines an encoded-buffer-size delta corresponding to the target intra-coded frame and the preceding intra-coded frame. Start encoded-buffer-size deltas graph 510 (see FIG. 5, discussed below) illustrates an exemplary signal derived from encoded-buffer-size deltas determined based on the preceding intra-coded frame within a time-window as having a small encoded-buffer size.

In decision block 335, subroutine 300 determines whether the determined encoded-buffer-size delta exceeds a predetermined segment-start threshold. If so, then subroutine 300 proceeds to block 340. Otherwise, subroutine 300 proceeds to decision block 345.

In some embodiments, the segment-start threshold may be expressed as a percentage of the range between the largest and the smallest encoded-buffer size within the given encoded video. In the exemplary implementation described in Appendix A, the segment-start threshold is determined to be 8% of the encoded-buffer-size range within the encoded video.

In block 340, subroutine 300 determines that one of a plurality of summarization segments starts at a timestamp associated with an encoded-buffer-size delta.

In decision block 345, subroutine 300 determines whether the target intra-coded frame is the last intra-coded frame of the given encoded video. If so, then subroutine 300 proceeds to ending block 399. Otherwise, subroutine 300 proceeds to block 350.

In block 350, subroutine 300 target next intra-coded frame.

Subroutine 300 ends in ending block 399, returning to the caller.

FIG. 4 illustrates a subroutine 400 for identifying an ending of a summarization segment of a given encoded video based at least in part on a plurality of encoded-buffer-size deltas, each indicating an encoded-buffer-size difference between a pair of intra-coded frames of a sequenced plurality of intra-coded frames, such as may be performed by a video-segment identification device 600 in accordance with one embodiment.

In block 405, subroutine 400 selects the first intra-coded frame of the given encoded video that has not already been processed.

In block 410, subroutine 400 determines the encoded-buffer size of the target intra-coded frame selected in block 405. The encoded-buffer size of the target intra-coded frame is available without decoding the given encoded video (which is computationally expensive) and represents the quantity of data that the lossy encoder allocated to the target intra-coded frame. Encoded-buffer sizes graph 505 (see FIG. 5, discussed below) illustrates a signal derived from the encoded-buffer sizes of intra-coded frames within an exemplary encoded video.

In block 415, subroutine 400 determines a time-window immediately preceding the target intra-coded frame, the time-window including a plurality of preceding intra-coded frames. In some embodiments, the time-window has a predetermined duration of, for example, between 1-5 seconds. In the exemplary implementation described in Appendix A, the immediately-preceding time-window has a duration of 3.5 seconds.

In block 420, subroutine 400 selects the preceding intra-coded frame within a time-window as having a large encoded-buffer size among a plurality of preceding intra-coded frames.

In block 425, subroutine 400 determines an encoded-buffer-size delta corresponding to the target intra-coded frame and the preceding intra-coded frame. Start encoded-buffer-size deltas graph 510 (see FIG. 5, discussed below) illustrates an exemplary signal derived from encoded-buffer-size deltas determined based on the preceding intra-coded frame within a time-window as having a large encoded-buffer size.

In decision block 430, subroutine 400 determines whether determined encoded-buffer-size delta exceeds a segment-end threshold (and other end-conditions satisfied). If so, then subroutine 400 proceeds to block 445. Otherwise, subroutine 400 proceeds to decision block 435.

In some embodiments, the segment-end threshold may be expressed as a percentage of the range between the largest and the smallest encoded-buffer size within the given encoded video. In the exemplary implementation described in Appendix A, the segment-end threshold is determined to be 8% of the encoded-buffer-size range within the encoded video.

In decision block 435, subroutine 400 determines whether the target intra-coded frame is the last intra-coded frame of the given encoded video.

In block 440, subroutine 400 target next intra-coded frame.

In block 445, subroutine 400 determines that one of a plurality of summarization segments ends at a timestamp associated with an encoded-buffer-size delta.

Subroutine 400 ends in ending block 499, returning to the caller.

FIG. 5 illustrates several exemplary sets of data resulting from various operations such as described herein.

Encoded-buffer sizes graph 505 illustrates a signal derived from the encoded-buffer sizes of intra-coded frames within an exemplary encoded video.

Start encoded-buffer-size deltas graph 510 illustrates a signal derived from the encoded-buffer-size deltas of encoded-buffer sizes of intra-coded frames within an exemplary encoded video. More specifically, start encoded-buffer-size deltas graph 510 illustrates a signal derived from encoded-buffer-size deltas determined based on a preceding intra-coded frame within a time-window as having a small encoded-buffer size, such as may be employed when scanning for a start of a summarization segment.

End encoded-buffer-size deltas graph 515 illustrates a signal derived from the encoded-buffer-size deltas of encoded-buffer sizes of intra-coded frames within an exemplary encoded video. More specifically, end encoded-buffer-size deltas graph 515 illustrates a signal derived from encoded-buffer-size deltas determined based on a preceding intra-coded frame within a time-window as having a large encoded-buffer size, such as may be employed when scanning for an end of a summarization segment.

Summarization segment candidates graph 520 illustrates an exemplary set of evaluation values of summarization segments of an exemplary encoded video based on a simplified evaluation of the signals shown in start encoded-buffer-size deltas graph 510 and end encoded-buffer-size deltas graph 515.

FIG. 6 illustrates several components of an exemplary video-segment identification device in accordance with one embodiment. In various embodiments, video-segment identification device 600 may include a desktop PC, server, workstation, mobile phone, laptop, tablet, set-top box, appliance, or other computing device that is capable of performing operations such as those described herein. In some embodiments, video-segment identification device 600 may include many more components than those shown in FIG. 6. However, it is not necessary that all of these generally conventional components be shown in order to disclose an illustrative embodiment.

In various embodiments, video-segment identification device 600 may comprise one or more physical and/or logical devices that collectively provide the functionalities described herein. In some embodiments, video-segment identification device 600 may comprise one or more replicated and/or distributed physical or logical devices.

In some embodiments, video-segment identification device 600 may comprise one or more computing resources provisioned from a “cloud computing” provider, for example, Amazon Elastic Compute Cloud (“Amazon EC2”), provided by Amazon.com, Inc. of Seattle, Wash.; Sun Cloud Compute Utility, provided by Sun Microsystems, Inc. of Santa Clara, Calif.; Windows Azure, provided by Microsoft Corporation of Redmond, Wash., and the like.

Video-segment identification device 600 includes a bus 605 interconnecting several components including a network interface 610, a display 615, a central processing unit 620, and a memory 625.

Memory 625 generally comprises a random access memory (“RAM”) and permanent non-transitory mass storage device, such as a hard disk drive or solid-state drive. Memory 625 stores program code for a routine 100 for automatically generating a video presentation summarizing one or more encoded videos (see FIG. 1, discussed above). In addition, the memory 625 also stores an operating system 635.

These and other software components may be loaded into memory 625 of video-segment identification device 600 using a drive mechanism (not shown) associated with a non-transitory computer-readable medium 630, such as a floppy disc, tape, DVD/CD-ROM drive, memory card, or the like.

Memory 625 also includes video-segment identification database 640. In some embodiments, video-segment identification device 600 may communicate with video-segment identification database 640 via network interface 610, a storage area network (“SAN”), a high-speed serial bus, and/or via the other suitable communication technology.

In some embodiments, video-segment identification database 640 may comprise one or more storage resources provisioned from a “cloud storage” provider, for example, Amazon Simple Storage Service (“Amazon S3”), provided by Amazon.com, Inc. of Seattle, Wash., Google Cloud Storage, provided by Google, Inc. of Mountain View, Calif., and the like.

Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that alternate and/or equivalent implementations may be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. For example, similar techniques may be applied to analyze signals other than the encoded-buffer sizes of intra-coded frames, such as the encoded-buffer sizes of inter-coded frames, the temporal location of subtitles in a video, and the like. This application is intended to cover any adaptations or variations of the embodiments discussed herein.

Following this description are Appendices A, which provide further information related to the subject matter disclosed herein.

More specifically, Appendix A includes pseudo-code illustrating one potential embodiment. 

The invention claimed is:
 1. A method, comprising: receiving a plurality of intra-coded frames of an encoded video; determining a start of a summarization segment for the encoded video as a first intra-coded frame of the plurality of intra-coded frames based on a first buffer-size delta between a first buffer size of the first intra-coded frame and a minimum buffer size of an intra-coded frame from a first set of the plurality of intra-coded frames exceeding a first threshold; and determining an end of the summarization segment as a second intra-coded frame of the plurality of intra-coded frames based on a second buffer-size delta between a second buffer size of the second intra-coded frame and a maximum buffer size of a second set of the plurality of intra-coded frames exceeding a second threshold.
 2. The method of claim 1, further comprising: selecting the first set of the plurality of intra-coded frames from the plurality of intra-coded frames that precede the first intra-coded frame.
 3. The method of claim 1, further comprising: selecting the first set of the plurality of intra-coded frames from the plurality of intra-coded frames that are within a time window that precedes the first intra-coded frame.
 4. The method of claim 1, further comprising: selecting the second set of the plurality of intra-coded frames from the plurality of intra-coded frames that precede the second intra-coded frame.
 5. The method of claim 1, further comprising: selecting the second set of the plurality of intra-coded frames from the plurality of intra-coded frames that are within a time window that precedes the second intra-coded frame.
 6. The method of claim 1, wherein determining the start of the summarization segment for the encoded video as the first intra-coded frame comprises: determining that the first buffer-size delta exceeds a segment start threshold.
 7. The method of claim 1, wherein determining the end of the summarization segment for the encoded video as the second intra-coded frame comprises: determining that the second buffer-size delta exceeds a segment end threshold.
 8. The method of claim 1, further comprising: generating a video presentation of the encoded video that includes the summarization segment.
 9. The method of claim 1, wherein determining the start of the summarization segment for the encoded video as the first intra-coded frame comprises: determining that a time duration between the first intra-coded frame and an end of a previous summarization segment exceeds a minimum duration.
 10. The method of claim 1, wherein determining the end of the summarization segment for the encoded video as the second intra-coded frame comprises: determining that a time duration between the first intra-coded frame and the second intra-coded frame exceeds a minimum duration.
 11. The method of claim 1, wherein determining the start of the summarization segment for the encoded video as the first intra-coded frame comprises: selecting the first intra-coded frame from the plurality of intra-coded frames; determining the first encoded-buffer size of the first intra-coded frame; determining a minimum buffer size of an intra-coded frame from the first set of the plurality of intra-coded frames; determining the first buffer-size delta between the first encoded-buffer size and the minimum buffer size; and identifying the first intra-coded frame as a start frame of the summarization segment in response to the first buffer-size delta exceeding a segment start threshold.
 12. The method of claim 1, wherein determining the end of the summarization segment for the encoded video as the second intra-coded frame comprises: selecting the second intra-coded frame from the plurality of intra-coded frames; determining the second encoded-buffer size of the second intra-coded frame; determining a maximum buffer size of an intra-coded frame from the second set of the plurality of intra-coded frames; determining the second buffer-size delta between the second encoded-buffer size and the maximum buffer size; and identifying the second intra-coded frame as an end frame of the summarization segment in response to the second buffer-size delta exceeding a segment end threshold.
 13. A non-transitory computer-readable storage medium having stored thereon instructions that when executed by a processor, cause the processor to perform actions, the actions comprising: receiving a plurality of intra-coded frames of an encoded video; selecting a first intra-coded frame from the plurality of intra-coded frames; determining a first encoded-buffer size of the first intra-coded frame; determining a minimum buffer size of an intra-coded frame from a first set of the plurality of intra-coded frames; determining a first delta between the first encoded-buffer size and the minimum buffer size; identifying the first intra-coded frame as a start frame of a summarization segment for the plurality of intra-coded frames in response to the first delta exceeding a first threshold; selecting a second intra-coded frame from the plurality of intra-coded frames; determining a second encoded-buffer size of the second intra-coded frame; determining a maximum buffer size of an intra-coded frame from a second set of the plurality of intra-coded frames; determining a second delta between the second encoded-buffer size and the maximum buffer size; and identifying the second intra-coded frame as an end frame of the summarization segment in response to the second delta exceeding a second threshold.
 14. The non-transitory computer-readable storage medium of claim 13, wherein the instructions that, when executed by the processor, cause the processor to perform further actions, the further actions comprising: selecting the first set of the plurality of intra-coded frames as intra-coded frames from the plurality of intra-coded frames that precede the first intra-coded frame; and selecting the second set of the plurality of intra-coded frames as intra-coded frames from the plurality of intra-coded frames that precede the second intra-coded frame.
 15. The non-transitory computer-readable storage medium of claim 13, wherein the instructions that, when executed by the processor, cause the processor to perform further actions, the further actions comprising: selecting the first set of the plurality of intra-coded frames from the plurality of intra-coded frames that are within a first time window that precedes the first intra-coded frame; and selecting the second set of the plurality of intra-coded frames from the plurality of intra-coded frames that are within a second time window that precedes the second intra-coded frame.
 16. The non-transitory computer-readable storage medium of claim 13, wherein identifying the first intra-coded frame as the start frame of the summarization segment comprises: determining that a time duration between the first intra-coded frame and an end of a previous summarization segment exceeds a minimum duration.
 17. The non-transitory computer-readable storage medium of claim 13, wherein identifying the second intra-coded frame as the end frame of the summarization segment comprises: determining that a time duration between the first intra-coded frame and the second intra-coded frame exceeds a minimum duration.
 18. The non-transitory computer-readable storage medium of claim 13, wherein the instructions that, when executed by the processor, cause the processor to perform further actions, the further actions comprising: generating a video presentation of the encoded video that includes the summarization segment.
 19. A computer, comprising: a non-transitory memory that stores computer instructions; and a processor communicatively coupled to the non-transitory memory that, in operation, executes the computer instructions to cause the processor to: obtain a plurality of intra-coded frames of an encoded video; select a first intra-coded frame from the plurality of intra-coded frames as a start frame of a summarization segment for the encoded video; and for each respective intra-coded frame of the plurality of intra-coded frames after the first intra-coded frame: determine a delta between an encoded-buffer size of the respective intra-coded frame and a maximum buffer size of an intra-coded frame from a set of the plurality of intra-coded frames that precede the respective intra-coded frame; and identify the respective intra-coded frame as an end frame of the summarization segment in response to the delta exceeding a segment end threshold.
 20. The computer of claim 19, wherein the processor selects the first intra-coded frame as the start of the summarization segment by executing the computer instructions to further cause the processor to: determine a second delta between an encoded-buffer size of the first intra-coded frame and a minimum buffer size of an intra-coded frame from a set of the plurality of intra-coded frames that precede the first intra-coded frame; and identify the first intra-coded frame as the start frame of the summarization segment in response to the second delta exceeding a segment start threshold. 